Power management integrated circuit with in situ non-volatile programmability

ABSTRACT

Disclosed is a power management integrated circuit including dual one-time programmable memory banks and methods for controlling the same. In one embodiment, the power management integrated circuit (PMIC) includes a first one-time programmable (OTP) memory bank; a second OTP memory bank; and access control logic, communicatively coupled to the first OTP bank and the second OTP bank, the access control logic configured to: utilize the first OTP memory bank for operation of the PMIC upon detecting that the second OTP memory bank is empty, write data to the second OTP memory bank in response to a write request from a host application if the second OTP memory bank is not empty, and utilize the second OTP memory bank for operation of the PMIC upon detecting that the second OTP memory bank is not empty.

FIELD OF THE TECHNOLOGY

At least some embodiments disclosed herein relate to power managementintegrated circuit (PMIC) in general and, more particularly but notlimited to, a PMIC with in situ non-volatile programmability.

BACKGROUND

A memory system can be a storage system, such as a solid-state drive(SSD), and can include one or more memory components that store data.For example, a memory system can include memory devices such asnon-volatile memory devices and volatile memory devices. In general, ahost system can utilize a memory system to store data at the memorydevices of the memory system and to retrieve data stored at the memorysystem.

A memory system can include a PMIC to manage the power requirements ofthe memory system in which the PMIC is configured. The PMIC typicallyincludes electronic power conversion circuitry and relevant powercontrol functions. A PMIC additionally allows for programmable controlof the functionality of the PMIC. For example, a PMIC may bereconfigured to change the power sequence, output voltages, and variousother functions of the PMIC.

Certain dedicated hardware is included within a PMIC package to supportprogrammatic control of the device. For example, a register file is usedfor storing values controlling the operation of the device. More recentPMICs incorporate non-volatile memory (e.g., electrically erasableprogrammable read-only memory, or, EEPROM) for storage of data. The useof non-volatile memory allows for storage of data values that persistsdespite (sometimes frequent) power cycles.

These conventional storage mechanisms in PMIC suffer from particulardeficiencies. A register file is a volatile storage device, and any datastored therein is lost during power cycling of the PMIC. Thus, despitebeing convenient for storage during operations, the register file failsto maintain data in the event of a power cycle, making it unsuitable forlonger-term value storage. This deficiency is particularly pronouncedduring development and testing of PMIC devices, where operationalparameters regarding the operation of the PMIC during power cycles isdesired to be tested.

The use of non-volatile memory, like EEPROM, enables long-term,reprogrammable storage of data. However, the circuitry required tosupport these memories (in addition to existing read-only memory)increases the size and power consumption of PMIC devices. For example, aPMIC with a read-only memory bank and an EEPROM bank requires twice thecircuitry for accessing the read-only memory bank as well as supportingerasing and writing to the EEPROM.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments are illustrated by way of example and not limitation inthe figures of the accompanying drawings in which like referencesindicate similar elements.

FIG. 1 is a block diagram of a power management integrated circuitaccording to some embodiments of the disclosure.

FIG. 2 is a flow diagram illustrating a method for toggling between OTPmemory banks according to some embodiments of the disclosure.

FIG. 3 illustrates an example computing environment that includes amemory system in accordance with some implementations of the presentdisclosure.

DETAILED DESCRIPTION

Aspects of the present disclosure are directed to a power managementintegrated circuit (PMIC) in a memory system. An example of a memorysystem is a storage system, such as a solid-state drive (SSD). In someembodiments, the memory system is a hybrid memory/storage system. Ingeneral, a host system can utilize a memory system that includes one ormore memory devices. The memory devices can include media. The media canbe non-volatile memory devices, such as, for example, negative- and(NAND). The host system can provide write requests to store data at thememory devices of the memory system and can provide read requests toretrieve data stored at the memory system. A memory system can include acontroller that manages the memory devices to perform operations such asreading data, writing data, or erasing data and other such operations. Astorage system (also hereinafter referred to as storage device) is usedas one example of the memory system hereinafter throughout thisdocument.

FIG. 1 is a block diagram of a power management integrated circuitaccording to some embodiments of the disclosure.

The PMIC (100) illustrated in FIG. 1 includes switch drivers (102),voltage regulators (104), sequencer (106), memory banks (108A, 108B),access control circuitry (116) and an interface (114). In oneembodiment, the PMIC (100) is connected to a host application (120) viaa bus (118), such as an I2C bus. In the illustrated embodiment, the hostapplication (120) comprises an external computing device that providesread and, more importantly, write commands to the PMIC (100). In theillustrated embodiment, interface (114) is configured to receive andtransmit commands over the bus (118) and forward write requests to theaccess control logic (116).

The PMIC (100) has one or more voltage regulators (104) that convert theexternal power supply to the PMIC (100) to operating voltages used byvarious components of the device (or devices) powered by the PMIC (100)(e.g., solid-state storage devices, DRAM, etc.). The PMIC (100) includesa plurality of switch drivers (102) that provide the control signals forthe load switches (not illustrated) that selectively enable and disablepower to and from the supported devices. The PMIC (100) includes asequencer (106) that schedules the power-related events according todesirable sequences for the operations of the supported devices,including the sequences of the operations of the voltage regulators(102) and the switch drivers (104).

PMIC (100) includes two memory banks (108A, 108B). In one embodiment,each memory bank (108A, 108B) comprises a one-time programmable (OTP)memory bank. In general, OTP memory allows for write-once, read-manyfunctionality. In the illustrated embodiment, each memory bank (108A,108B) comprises the same type of memory, although, in some embodiments,the memory banks (108A, 108B) may comprise differing OTP memorytechnologies. In some embodiments, memory banks (108A, 108B) areidentically sized while in other embodiments the size of each memorybank (108A, 108B) may be adjusted based on the needs of the PMIC (100).For example, memory bank (108B) may be sized larger than memory bank(108A) to compensate for the single-write aspects of the memory bank(e.g., multiple versions of parameters may be stored duringdevelopment). On the other hand, memory bank (108A) may be sized largerthan memory bank (108B) to support vendor-specific parameters.

As described above, memory banks (108A, 108B) store parameters (124A,124B) controlling the operation of the PMIC (100) including circuitry(102-106). Various circuits of the PMIC (100) access the memory banks(108A, 108B) and utilize the stored parameters to control theiroperation. Parameters (124B) are dashed in FIG. 1 to illustrate an emptybank (108B).

Both memory banks (108A, 108B) may include a write enable pin, pad, orconnector (referred to generally as a “write enable”). This write enablecontrols whether writing is possible to the memory bank, regardless ofwhether the memory bank has already been written to, thus converting thememory bank into a write-never memory device. One write enable (112) isillustrated in the memory bank (108B) however in some embodiments memorybank (108A) also may include a write enable.

As illustrated, one memory bank (108A) includes a dedicated bit (110).This dedicated bit (110) drives the write enable (112) of the secondmemory bank (108B). In some embodiments, other signals may also drivethe write enable (112), and these signals, combined with bit (110) maybe multiplexed to control writing to the bank (108B). In the illustratedembodiment, bit (110) comprises a fixed location in the bank (108A). Forexample, a specific bit in a specific memory location may be used as thebit (110). In one embodiment, the bit (110) is hardwired to the writeenable (112) thus automatically enabling/disabling the bank (108B) whenthat bit is written. For example, if bit (110) is set to one, writing tothe bank (108B) is enabled; while if bit (110) is set to zero, writingto the bank (108B) is disabled.

In one embodiment, bank (108A) is written to during manufacturing of thePMIC (100). Thus, in one embodiment, a manufacturer may write a one orzero to bit (110) achieving the effect of providing or not providing,respectively, one-time programmable features to the PMIC (100).

PMIC (100) additionally includes access control logic (116) whichcontrols access to banks (108A, 108B). In one embodiment, access controllogic (116) may comprise a controllable switch or fuse that switchesbetween banks (108A, 108B).

In an initial state, access control logic (116) is switched to provideaccess to the bank (108A) (e.g., to circuits 102-106). The accesscontrol logic (116) may later receive a write request from hostapplication (120) via an interface (114). In one embodiment, the accesscontrol logic (116) includes a second switch driven by the write enable(112) that determines whether data in the write request may be writtento the bank (108B). If the write enable (112) is enabled, access controllogic (116) permits the writing to the bank (108B). After writing iscomplete, the access control logic (116) toggles the first switch suchthat future requests from circuits (102-106) are routed automatically tothe second bank (108B).

FIG. 2 is a flow diagram illustrating a method for toggling between OTPmemory banks according to some embodiments of the disclosure. In oneembodiment, the method performed in FIG. 2 is performed by a PMIC. Inone embodiment, operations at blocks 206-222C may be controlled byaccess control logic in the PMIC, while other steps may be performed byother components of the PMIC (or in response to external inputs).

At block 202, bank A is programmed. As described above, bank A comprisesan OTP memory bank. In one embodiment, bank A is programmed by amanufacturer of the PMIC, although the specific programmer is notintended to be limited. As discussed above, bank A includes allnon-volatile parameters needed to operate the PMIC.

At block 204, the method powers on the PMIC device. In one embodiment,powering on the PMIC device causes the circuits of the PMIC device toissue read requests to the PMICs memory to retrieve operationalparameters.

At block 206, the method determines whether data has been written tobank B. As described above, bank B may also comprise an OTP memory bankthat is uninitialized during manufacturing and, potentially, written toafter manufacturing.

In one embodiment, the operation at block 206 is performed in responseto a request for data from the circuitry of the PMIC. In one embodiment,step 206 may be performed by a CMOS or similar switch within the accesscontrol logic of the PMIC. In another embodiment, the operation at block206 may be performed immediately upon powering the PMIC.

If bank B is empty (i.e., not written to), the method sets bank A as theparameter source at block 208. In one embodiment, between block 208 and210, the method may receive one or more requests for data from thecircuitry of the PMIC (Mock 222A). In response to these requests, themethod responds to the requests with the data stored in bank A. Theserequests may continue until a write request is received and may continueduring the actual write request.

At block 210, the method receives a write request. In one embodiment,the write request includes data to be written to bank B. In oneembodiment, the write request is received from a host application over abus and interface, as described previously.

At block 212, the method determines if writing is enabled for bank B. Inone embodiment, the method makes this determination by detecting whethera write enable signal is enabled or disabled for bank B. In oneembodiment, the operation at block 212 additionally includes determiningwhether data has already been written to bank B.

If the writing is not enabled, the method continues to handle parameterrequests from circuitry using bank A (block 222B). This processcontinues until power to the PMIC is cycled (block 220).

Alternatively, if the method determines that writing is enabled at block212, the method writes the contents of the write request to bank B atblock 214. In some embodiments, the write request may include all datato be written to bank B. In other embodiments, the write request maycomprise multiple sub-requests including data to be written, delimitedby START and STOP commands.

At block 216, after writing to bank B is complete, the method sets bankB as the parameter source for future requests and handles parameterrequests using bank B (block 222C) for future requests until power iscycled (block 220).

Returning to block 206, if the method determines that bank B has beenwritten to in response to a power on or power cycle, the method ignoresany future write requests (block 218). Since bank B has been written to,the method proceeds to handle all parameter requests from bank B (block222C) until power cycling.

FIG. 3 illustrates an example computing environment 300 that includes amemory system 310 in accordance with some implementations of the presentdisclosure. The memory system 310 can include media, such as memorydevices 312A to 312N. The memory devices 312A to 312N can be volatilememory devices, non-volatile memory devices, or a combination of such.In some embodiments, the memory system is a storage system. An exampleof a storage system is a SSD. In some embodiments, the memory system 310is a hybrid memory/storage system. In general, the computing environment300 can include a host system 320 that uses the memory system 310. Insome implementations, the host system 320 can write data to the memorysystem 310 and read data from the memory system 310.

The host system 320 can be a computing device such as a desktopcomputer, laptop computer, network server, mobile device, or suchcomputing device that includes a memory and a processing device. Thehost system 320 can include or be coupled to the memory system 310 sothat the host system 320 can read data from or write data to the memorysystem 310. The host system 320 can be coupled to the memory system 310via a physical host interface. As used herein, “coupled to” generallyrefers to a connection between components, which can be an indirectcommunicative connection or direct communicative connection (e.g.,without intervening components), whether wired or wireless, includingconnections such as, electrical, optical, magnetic, etc. Examples of aphysical host interface include, but are not limited to, a serialadvanced technology attachment (SATA) interface, a peripheral componentinterconnect express (PCIe) interface, universal serial bus (USB)interface, Fibre Channel, Serial Attached SCSI (SAS), etc. The physicalhost interface can be used to transmit data between the host system 320and the memory system 310. The host system 320 can further utilize anNVM Express (NVMe) interface to access the memory devices 312A to 312Nwhen the memory system 310 is coupled with the host system 320 by thePCIe interface. The physical host interface can provide an interface forpassing control, address, data, and other signals between the memorysystem 310 and the host system 320.

The memory devices 312A to 312N can include any combination of thedifferent types of non-volatile memory devices and/or volatile memorydevices. An example of non-volatile memory devices includes a negative-and (NAND) type flash memory. Each of the memory devices 312A to 312Ncan include one or more arrays of memory cells such as single levelcells (SLCs) or multi-level cells (MLCs) (e.g., triple level cells(TLCs) or quad-level cells (QLCs)). In some implementations, aparticular memory device can include both an SLC portion and a MLCportion of memory cells. Each of the memory cells can store bits of data(e.g., data blocks) used by the host system 320. Although non-volatilememory devices such as NAND type flash memory are described, the memorydevices 312A to 312N can be based on any other type of memory such as avolatile memory. In some implementations, the memory devices 312A to312N can be, but are not limited to, random access memory (RAM),read-only memory (ROM), dynamic random access memory (DRAM), synchronousdynamic random access memory (SDRAM), phase change memory (PCM), magnetorandom access memory (MRAM), negative- or (NOR) flash memory,electrically erasable programmable read-only memory (EEPROM), and across-point array of non-volatile memory cells. A cross-point array ofnon-volatile memory can perform bit storage based on a change of bulkresistance, in conjunction with a stackable cross-gridded data accessarray. Additionally, in contrast to many Flash-based memory, cross pointnon-volatile memory can perform a write in-place operation, where anon-volatile memory cell can be programmed without the non-volatilememory cell being previously erased. Furthermore, the memory cells ofthe memory devices 312A to 312N can be grouped as memory pages or datablocks that can refer to a unit of the memory device used to store data.

The controller 315 can communicate with the memory devices 312A to 312Nto perform operations such as reading data, writing data, or erasingdata at the memory devices 312A to 312N and other such operations. Thecontroller 315 can include hardware such as one or more integratedcircuits and/or discrete components, a buffer memory, or a combinationthereof. The controller 315 can be a microcontroller, special purposelogic circuitry (e.g., a field programmable gate array (FPGA), anapplication specific integrated circuit (ASIC), etc.), or other suitableprocessor. The controller 315 can include a processor (processingdevice) 317 configured to execute instructions stored in local memory319. In the illustrated example, the local memory 319 of the controller315 includes an embedded memory configured to store instructions forperforming various processes, operations, logic flows, and routines thatcontrol operation of the memory system 310, including handlingcommunications between the memory system 310 and the host system 320. Insome embodiments, the local memory 319 can include memory registersstoring, e.g., memory pointers, fetched data, etc. The local memory 319can also include read-only memory (ROM) for storing micro-code. Whilethe example memory system 310 in FIG. 3 has been illustrated asincluding the controller 315, in another embodiment of the presentdisclosure, a memory system 310 may not include a controller 315, andmay instead rely upon external control (e.g., provided by an externalhost, or by a processor or controller separate from the memory system).

In general, the controller 315 can receive commands or operations fromthe host system 320 and can convert the commands or operations intoinstructions or appropriate commands to achieve the desired access tothe memory devices 312A to 312N. The controller 315 can be responsiblefor other operations such as wear leveling operations, garbagecollection operations, error detection and error-correcting code (ECC)operations, encryption operations, caching operations, and addresstranslations between a logical block address and a physical blockaddress that are associated with the memory devices 312A to 312N. Thecontroller 315 can further include host interface circuitry tocommunicate with the host system 320 via the physical host interface.The host interface circuitry can convert the commands received from thehost system into command instructions to access the memory devices 312Ato 312N as well as convert responses associated with the memory devices312A to 312N into information for the host system 320.

The memory system 310 can also include additional circuitry orcomponents that are not illustrated. In some implementations, the memorysystem 310 can include a cache or buffer (e.g., DRAM) and addresscircuitry (e.g., a row decoder and a column decoder) that can receive anaddress from the controller 315 and decode the address to access thememory devices 312A to 312N.

The memory system 310 can include PMIC 311 (e.g., PMIC 100 in FIG. 1).The memory system 310 can include additional circuitry, such asillustrated in FIG. 1.

In this description, various functions and operations may be describedas being performed by or caused by computer instructions to simplifydescription. However, those skilled in the art will recognize what ismeant by such expressions is that the functions result from execution ofthe computer instructions by one or more controllers or processors, suchas a microprocessor. Alternatively, or in combination, the functions andoperations can be implemented using special purpose circuitry, with orwithout software instructions, such as using Application-SpecificIntegrated Circuit (ASIC) or Field-Programmable Gate Array (FPGA).Embodiments can be implemented using hardwired circuitry withoutsoftware instructions, or in combination with software instructions.Thus, the techniques are limited neither to any specific combination ofhardware circuitry and software, nor to any particular source for theinstructions executed by the data processing system.

While some embodiments can be implemented in fully functioning computersand computer systems, various embodiments are capable of beingdistributed as a computing product in a variety of forms and are capableof being applied regardless of the particular type of machine orcomputer-readable media used to actually effect the distribution.

At least some aspects disclosed can be embodied, at least in part, insoftware. That is, the techniques may be carried out in a computersystem or other data processing system in response to its processor,such as a microprocessor or microcontroller, executing sequences ofinstructions contained in a memory, such as ROM, volatile RAM,non-volatile memory, cache or a remote storage device.

Routines executed to implement the embodiments may be implemented aspart of an operating system or a specific application, component,program, object, module or sequence of instructions referred to as“computer programs.” The computer programs typically comprise one ormore instructions set at various times in various memory and storagedevices in a computer, and that, when read and executed by one or moreprocessors in a computer, cause the computer to perform operationsnecessary to execute elements involving the various aspects.

A tangible, non-transitory computer storage medium can be used to storesoftware and data which, when executed by a data processing system,causes the system to perform various methods. The executable softwareand data may be stored in various places including for example ROM,volatile RAM, non-volatile memory and/or cache. Portions of thissoftware and/or data may be stored in any one of these storage devices.Further, the data and instructions can be obtained from centralizedservers or peer-to-peer networks. Different portions of the data andinstructions can be obtained from different centralized servers and/orpeer-to-peer networks at different times and in different communicationsessions or in a same communication session. The data and instructionscan be obtained in their entirety prior to the execution of theapplications. Alternatively, portions of the data and instructions canbe obtained dynamically, just in time, when needed for execution. Thus,it is not required that the data and instructions be on amachine-readable medium in their entirety at a particular instance oftime.

Examples of computer-readable storage media include, but are not limitedto, recordable and non-recordable type media such as volatile andnon-volatile memory devices, read only memory (ROM), random accessmemory (RAM), flash memory devices, floppy and other removable disks,magnetic disk storage media, and optical storage media (e.g., CompactDisk Read-Only Memory (CD ROM), Digital Versatile Disks (DVDs), etc.),among others. The instructions may be embodied in a transitory medium,such as electrical, optical, acoustical or other forms of propagatedsignals, such as carrier waves, infrared signals, digital signals, etc.A transitory medium is typically used to transmit instructions, but notviewed as capable of storing the instructions.

In various embodiments, hardwired circuitry may be used in combinationwith software instructions to implement the techniques. Thus, thetechniques are neither limited to any specific combination of hardwarecircuitry and software, nor to any particular source for theinstructions executed by the data processing system.

Although some of the drawings illustrate a number of operations in aparticular order, operations that are not order dependent may bereordered and other operations may be combined or broken out. While somereordering or other groupings are specifically mentioned, others will beapparent to those of ordinary skill in the art and so do not present anexhaustive list of alternatives. Moreover, it should be recognized thatthe stages could be implemented in hardware, firmware, software or anycombination thereof.

The above description and drawings are illustrative and are not to beconstrued as limiting. Numerous specific details are described toprovide a thorough understanding. However, in certain instances, wellknown or conventional details are not described in order to avoidobscuring the description. References to one or an embodiment in thepresent disclosure are not necessarily references to the sameembodiment; and, such references mean at least one.

In the foregoing specification, the disclosure has been described withreference to specific exemplary embodiments thereof. It will be evidentthat various modifications may be made thereto without departing fromthe broader spirit and scope as set forth in the following claims. Thespecification and drawings are, accordingly, to be regarded in anillustrative sense rather than a restrictive sense.

What is claimed is:
 1. A power management integrated circuit (PMIC)comprising: a first one-time programmable (OTP) memory bank; a secondOTP memory bank, wherein the first OTP memory bank comprises a firstbit, the first bit controlling write access to the second OTP memorybank, the first bit being hardwired to a write enable of the second OTPmemory bank; and access control logic, communicatively coupled to thefirst OTP memory bank and the second OTP memory bank, the access controllogic configured to: utilize the first OTP memory bank for operation ofthe PMIC upon detecting that the second OTP memory bank is empty, writedata to the second OTP memory bank in response to a write request from ahost application if the second OTP memory bank is not empty, and utilizethe second OTP memory bank for operation of the PMIC upon detecting thatthe second OTP memory bank is not empty.
 2. The PMIC of claim 1, whereinthe first OTP memory bank is pre-programmed prior to use and the secondOTP memory bank is empty prior to use.
 3. The PMIC of claim 1, theaccess control logic further configured to select between the first OTPmemory bank and the second OTP memory bank after a power cycle.
 4. ThePMIC of claim 1, the access control logic further configured to ignorethe write request if the second OTP memory bank is not empty.
 5. ThePMIC of claim 1, further comprising an interface configured to receivethe write request over a bus.
 6. The PMIC of claim 5, the write requestconforming to an I2C protocol message.
 7. The PMIC of claim 1, furthercomprising at least one of switch driver, a voltage regulator, or asequencer.
 8. The PMIC of claim 1, further comprising a switch driver,the switch driver configured to drive a solid-state storage device.
 9. Amethod comprising: determining, by a power management integrated circuit(PMIC), whether a second one-time programmable (OTP) memory bankcontains data; utilizing, by the PMIC, a first OTP memory bank as aparameter source if the second OTP memory bank does not contain data;enabling, by the PMIC, write access to the second OTP memory bank bywriting to a first bit in the first OTP memory bank, the first bit beinghardwired to a write enable of the second OTP memory bank; writing, bythe PMIC, data to the second OTP memory bank in response to a writerequest from a host application if the second OTP memory bank is notempty; and utilizing, by the PMIC, the second OTP memory bank as aparameter source if the second OTP memory bank does contain data. 10.The method of claim 9, the determining whether the second OTP memorybank contains data performed in response to powering on the PMIC. 11.The method of claim 10, the powering on the PMIC resulting from a powercycle.
 12. The method of claim 9, the writing data to the second OTPmemory bank performed upon determining that writing is enabled for thesecond OTP memory bank.
 13. The method of claim 12, the determining thatwriting is enabled for the second OTP memory bank comprising analyzingthe write enable of the second OTP memory bank.
 14. The method of claim9, the utilizing the first OTP memory bank as a parameter source andutilizing the second OTP memory bank as a parameter source bothcomprising supply parameters from a respective memory bank to circuitryof the PMIC.
 15. The method of claim 9, further comprisingpre-programming the first OTP memory bank prior to use.
 16. The methodof claim 15, the second OTP memory bank being uninitialized prior touse.
 17. The method of claim 9, further comprising ignoring the writerequest if data is stored in the second OTP memory bank.
 18. The methodof claim 9, further comprising receiving the write request from the hostapplication over a bus.